1. Field of the Invention
The present invention relates to a camera system which performs such an exposure action as to emit light toward an object of shooting from a flash device employed as flash light emitting means and adjusts the amount of light emission to automatically obtain an apposite exposure, and more particularly, relates to a camera system and a flash photography system each of which is capable of a multi-flash-device photography in which two or more flash light emitting means are used for photography.
2. Description of Related Art
It has heretofore been known to simultaneously control and cause two or more flash devices to illuminate one object of shooting, such as a person, from different directions for the purpose of stereoscopically depicting the object or for erasing some shadow produced by the light of one of the light emitting parts with that of another. This method is called a multi-flash-device photography.
In the multi-flash-device photography, the result of photographing varies according to the ratio of the light amount of each individual flash device to the total light amount of the plurality of flash devices. It is, therefore, important to have the light amount of each of these flash devices controlled as desired by the user of the camera system. In that respect, the multi-flash-device photography is performed in varied patterns. For example, one of the flash devices is used for illuminating only the background of a scene so as to erase a shadow on the background or to strengthen the color of the background.
According to a known technique, a total amount of light to be emitted by a plurality of flash devices is controlled to an apposite amount in a predetermined ratio of light emission amounts, for example, in the following manner. Two flash devices are simultaneously caused to begin to emit light to obtain reflected light from the object of shooting. The reflected light from the object is measured and integrated. One of the two flash devices is stopped from emitting light when the reflected light reaches a first predetermined amount and the other flash device is stopped from emitting light when the reflected light reaches a second predetermined amount.
A camera system disclosed in DE 3346757 (Bron Elektronik) is arranged to obtain an apposite amount of exposure by making preliminary light emission from a plurality of flash devices in a preset light amount ratio in the multi-flash-device photography, measuring reflected light thus obtained from an object of shooting, and using the obtained result of light measurement for making main light emission.
According to another method disclosed in Japanese Laid-Open Patent Application No. HEI 6-180472, two flash devices are respectively caused to make preliminary light emission, the amounts of reflected light from an object of shooting resulting from the preliminary light emission by the two flash devices are respectively measured, the amounts of main light emission to be made by the two flash devices are computed separately from each other, and the main light emission for exposure is controlled on the basis of the results of the computing operations.
However, the camera system disclosed in the above Japanese Laid-Open Patent Application No. HEI 6-180472 is arranged to measure the amount of reflected light of the object resulting from the preliminary light emission by using a sensor which is arranged to simply integrate a photoelectric current and convert it into a voltage. Therefore, the dynamic range of the sensor is narrow. As a result, when a predetermined value has not been able to be obtained by the preliminary light emission due to the narrow dynamic range, that arrangement necessitates the preliminary light emission to be made again by varying the number of pulses for preliminary light emission to vary a total light amount of the preliminary light emission.